Refractive index converter
Convert refractive index into the critical angle, Brewster’s angle and how much light bounces off the surface.
That's 1.13× as dense as water, while window glass is 1.01× higher. Light travels 1.5 times slower inside it.
What it means
How much does it bend light?
Index depends on wavelength — that is what makes a prism work. Published values are usually for the yellow sodium line at 589 nm.
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Learn
Three things worth knowing
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Critical angle = arcsin(1 ÷ n)
Water at 1.33 gives 48.8°, glass at 1.5 gives 41.8°, and diamond at 2.42 gives 24.4°. The narrow escape cone is why diamonds sparkle.
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Snell, and before him Ibn Sahl
Ibn Sahl wrote the refraction law down in Baghdad in 984, six centuries before Snell. Both were describing the same ratio of sines.
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Index is not density
Diamond and graphite are both carbon; one has an index of 2.42 and the other is opaque. What matters is how the electrons respond to light, not how heavy the material is.
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Background
About refractive index
Light travels slower inside a material, and n says by how much: at n = 1.5, light crawls along at two thirds of its vacuum speed. That slowing is what bends the beam.
It also fixes the critical angle: past 41.8° inside glass, light cannot get out at all, which is how optical fiber works.